1. Field
This document relates to an electron transport compound and an organic light emitting device comprising the same.
2. Related Art
In general, an organic light emitting display is a self-emitting display for emitting light by electrically exciting a fluorescent compound and has been spotlighted as a future generation display that can solve problems of a liquid crystal display as it can be driven in a low voltage, easily reduce a thickness, have a wide viewing angle and a fast response speed, etc.
The organic light emitting device comprises an organic emitting layer between an anode and a cathode. The organic light emitting device forms an exciton, which is a hole-electron pair, by coupling a hole received from the anode and an electron received from the cathode within the organic light emitting layer and emits light by generating energy when the exciton returns to a ground level. The organic light emitting device further comprises a hole (electron) injecting layer and/or a hole (electron) transporting layer between the anode or the cathode and the emitting layer.
A process of manufacturing organic light emitting device is as follows.
(1) First, an anode is formed on a transparent substrate. As the material for anode, Indium Tin Oxide (ITO) is generally used.
(2) A hole injecting layer (HIL) is formed on the anode. As the HIL, copper phthalocyanine (CuPc) is generally used and the thickness of the HIL is 10 nm to 30 nm.
(3) Next, a hole transport layer (HTL) is formed on the HIL. As the hole transport layer, 4,4′-bis[N-(1-naphthyl)-N-phenthylamino]-biphenyl (NPB) is generally used and the thickness of the HTL is 30 nm to 60 nm.
(4) An organic emitting layer is formed on the HTL. The organic emitting layer may comprise a host and a dopant. In a case of green light emitting layer, tris(8-hydroxy-quinolatealuminum (Alq3) as the host is deposited in a thickness of about 30 to 60 nm and as a dopant, N-Methylquinacridone (MQD) is doped in the host.
(5) An electron transport layer (ETL) and an electron injecting layer (EIL) are consecutively formed or one electron injecting and transport layer is formed on the organic emitting layer. In a case of green light emitting layer, because Alq3 of (4) has good electron transport ability, an electron injecting/transport layer may not be separately used.
(6) Next, a cathode is formed and finally a protective layer is stacked.
However, conventional organic light emitting device, particularly, an electron transport compound for an electron injecting layer or an electron transport layer has problems of low electron transport efficiency in using for a display device and difficulty of deposition. Further, a conventional electron transport compound has a problem of a short lifetime due to high possibility of crystallization and deterioration.